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From a logic standpoint, if you are generating
current, you are doing work -- doing work requires the expenditure of energy.
Therefore when you put a load on the alternator, it must draw power from the
engine, and increase the fuel burn -- or decrease the amount of power available
for other purposes.
If you want to test this, take a small electric
motor (such as from a fan) that doesn't have lots of power. hook it up to drive
the alternator with no field current, and then turn the field current on and
watch the speed change.
Bill Schertz
KIS Cruiser #4045
N343BS
----- Original Message -----
Sent: Thursday, March 19, 2009 8:08
AM
Subject: [FlyRotary] Alternator (Off
topic)
Since it's
quiet:
When I was a kid a guy at
the parts store demonstrated to my Dad that when electrical power was needed,
a generator put a load on the engine. After that, my Dad was careful not to
run lights, radio, heater fan, or other non-essentials when he was trying to
get good gas mileage.
I have continued that
tradition, however, I have seen it stated that electrical draw on an
alternator doesn't increase the mechanical load.
When low on fuel will it
help to turn off electrical components not needed for flight?
Is it true of an
alternator; an electrical power demand doesn't cause an increased mechanical
load?
Or, does keeping
headlights on during the day decrease gas mileage?
Thanks!
Ben
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